Internal combustion engines, for example, diesel engines, gasoline engines, or natural gas engines employ turbochargers to deliver compressed air for combustion in the engine. A turbocharger compresses air flowing into the engine, helping to force more air into the combustion chambers of the engine. The increased supply of air allows increased fuel combustion in the combustion chambers of the engine, resulting in increased power output from the engine.
A typical turbocharger includes a shaft, a turbine wheel attached to one end of the shaft, a compressor impeller connected to the other end of the shaft, and bearings to support the shaft. Often a turbine housing surrounds the turbine wheel and a separate compressor housing surrounds the compressor impeller. In addition, the turbocharger may include a bearing housing that surrounds the bearings and includes features that help prevent leakage of bearing lubrication oil into the turbine housing or the compressor housing. The turbine housing, the compressor housing, and the bearing housing are attached to each other via fasteners or other clamping mechanisms.
Hot exhaust from the engine flows through the turbine housing and expands over the turbine wheel, rotating the turbine wheel and the shaft connected to the turbine wheel. The shaft in turn rotates the compressor impeller. Relatively cool air from the ambient flows through the compressor housing where the compressor impeller compresses the air and drives the compressed air into the combustion chambers of the engine. Because the exhaust from the engine is significantly hotter than the ambient air, the turbine housing can experience temperatures significantly higher than the compressor housing. The bearing housing, lying between the turbine housing and the compressor housing, experiences temperatures relatively lower than that of the turbine housing and relatively higher than that of the compressor housing. Because of the different temperatures of the turbine housing, the compressor housing, and the bearing housing, these components may experience different amounts of thermal expansion. The differential thermal expansion causes relative motion between the turbine housing, the compressor housing, and the bearing housing, making it difficult to keep these components securely fastened to each other during operation of the turbocharger. Moreover, the relative motion may also induce mechanical fatigue in the connecting fasteners, reducing the useful life of the fasteners.
One attempt to address some of the problems described above is disclosed in U.S. Patent Application Publication No. 2011/0299983 of Delitz published on Dec. 8, 2011 (“the '983 publication”). In particular, the '983 publication discloses a connection assembly of a turbine housing to a bearing housing. The '983 publication discloses that the bearing housing is connected to the turbine housing by means of a connection device in the form of a V collar clamp. The '983 publication also discloses that a heat shield is arranged between the bearing housing and the turbine housing to prevent heat from being transferred from the turbine housing to the bearing housing. The '983 publication discloses that the heat shield extends to a region between the contacting flange shaped portions of the turbine housing and the bearing housing.
Although the connection assembly disclosed in the '983 publication attempts to minimize the transfer of heat from the turbine housing to the bearing housing, the disclosed connection assembly may still be less than optimal. In particular, by preventing the flow of heat from the turbine housing to the bearing housing, the heat shield of the '983 publication may exacerbate the differences in thermal expansion of the bearing housing and the turbine housing. The disclosed V clamp of the '983 publication may also be subject to mechanical fatigue because of the differential expansion between the bearing housing and the turbine housing. Further, because the V clamp of the '983 publication resides external to the bearing housing and the turbine housing, the V clamp may be exposed to moisture and other corrosive elements, which may degrade the V clamp and reduce its useful life.
The turbine housing assembly of the present disclosure solves one or more of the problems set forth above and/or other problems of the prior art.